Hydraulic valve mechanism



May 6, 1930. G. E. A. HALLETT HYDRAULIC VALVE MECHANISM Filed April llI 1927 atented lwl GEORGE E. A. HALLETT, DETROIT, MICHIGAN, ASSIGNOB. TO GENERAL MOTORS RESEARCH CORPORATION, OF DETROIT, MICHIGAN, A. CORPORATION OF DELAWARE HYDUILIIC 'VALVE MECHANISM 'application filed april 11,

'Ihis invention relates to hydraulic operating mechanism and particularly to mechanism of this type designed to operate the valves of internal combustion engines. It is m an improvement on the construction shown in my prior application, Serial No. 126,297

liled July 31st, 1926. In that application` there is disclosed an hydraulic chamber containing iiuid such as lubricating oil thru m which motion is transmitted from an operating plunger to an operated plunger, the former being engaged by the usual push rod whole the latter engages the valve stem. With this construction, the push rod carries ia the operating plunger with it on its upwardv stroke resulting in displacement of fluid in the hydraulic chamber which causes the operated plunger to be forced downwardly against the valvestem unseating the valve. a To insure thatthe operating plunger will at all times follow thetappet, a light coil spring encircles the plunger and continuously urges it into engagement with the tappet. A similar spring is provided on the operated 2t plunger.

While the described construction will operate satisfactorily, it has been found that the coil springs are a source of noise and to some extent interfere with valve operation, particularly when operated at speeds approaching their natural frequency of vibration.

Somewhat more satisfactory operation may be obtained by using torsion or leaf springs in place of coil springs, but I have found that the difficulty may be entirely overcome by employing a spring construction such that while constantly holding the plunger in contact with the valve or push rod, the spring is not periodically flexed or distorted during normal operation of the gear. This is accomplished by employing a leaf or bar spring pivoted at an intermediate or nodal point and aving its" ends engaging the respective plungers. The spring, when put in place, is given an initial stress such that it at al1 timestends to force the plungers downwardly into engagement with the tappet or valve stem. Were the plungers-of equal displace- 50 ment, the lengths of their strokes during northe latter.

1927. Serial No. 132,935.

mal operationof the gear would be equal and the rocker pivot would lie on a line midway between the plungers. However, it is usually found desirable to employ an operating plunger of greater displacement than the operated plunger thus enabling the use of a cam of lower lift and consequently quieter operation. In such designs, the stroke of the operating plunger is less than ythat of the operated plunger; consequently, the pivot of the rocker must lie nearer the former than As the location of the rocker pivot is thus iixedby the lengths ofA strokes of the plungers, I have, for lack of a better term, referred to the fulcrum point thus determined as a nodal point. It is obvious that this point may lie anywhere along a line drawn'between the plungers parallel to their path of movement and spaced from the plungers in proportion to the lengths of their strokes.y

rlhe employment of a spring which, while in a constant state of stress is subject to little or no periodic flexing, permits working the sprin near its elastic limit. This means that a lig ter spring may be employed than would otherwise be required and consequently reduces cost. More important, by thus reducing the weight of the moving parts, less energy is consumed in operating the gear. rI'he spring is preferably so mounted that it i serves as a means to hold the plungers in their hores when removing the head to permit access to tappetsA and valves as when it is desired to grind the latter. It is obvious that this function may be performed by springs of other types or by non-resilient parts, if preferred.

In thedrawings, Figure 1 is a vertical section thru a portion of an automobile engine equipped with hydraulic valve gear embodying my invention. Figure 2 is an enlarged view of the lower portion of the plungers and the rocker spring, as shown in Figure l, but with the parts removed from the engine.

FiEgure 3 is a section on line 3 3 of Figure 2. igure 4 is a fragmentary view showing modified forms of plungers and rockerspring.

Figure 5 is a plan view of the spring of 1 Figure a.

isl supplied with oil from reservoir` 16 thru l inlet valve 18 shown as of the leaf spring type. The specic arrangement of the hydraulic mechanism in so tar as it diliers from that shown in my prior application` and is not claimed herein is described and claimed in an application of John O. Almen. I have' shown at 20 a plug thru which oil may be supplied to the valve chamber and thru which air may be dischargedwhen desired.

In the construction shown, the guides for the plungers 10 and 12 and the reservoir 16 are formed in a casting 22 which is in the form of a head superposed on the usual cylinder head. The hydraulic chamber 14 is lformed in a cover 24 bolted to the head22.

A fork 26 projects downwardly from the underside of the reservoir 16 and 'serves as a tulcrum for my rocker spring,.to be later described. It is to be understood that a separate chamber 14, as well as operating and operated plungers, is provided for each of the valves. The cover 24 may be divided by suitable partitions to provide the separate reservoirs, The reservoir 16 is designed to serve a number of chambers and I have shown it supplied with oil from a suitable source, such as the crankcase, thru conduit 28. The oil 1s pumped into the chamber by the usual pump serving for `the lubrication of the engine. To insure against the draining ofthe reservoir 16 when the engine is idle, a suitable check valve may be provided in the conduit 28. c

My improved spring is shown at 30. As best shown in Figure 3, it comprises a transverse portion 32 held in the ork 26 by any' suitable means, suchv as a cotter pin 34. The portion 32 is provided with return bent por.- tions 36 and 38 terminating in longitudinal portions l4() and 42. The portion 40 has a rocking and sliding fit in an aperture 44 formed in an extension of the operating plunger l0, while the portion 42 is similarly vfitted in an .aperture 46 in an extension ofy `the operated plunger 12.

It will be apparent that the engagement of the ends of the springl with the plungers .prevents them dropping out of their guides.

Figure 2 shows the relation of spring and plungers when the head 22 is removed from the engine. It will be noted that the spring is here shown in its :tree or unstressed position and it will be observed that the portions on opposite sides of the transverse portion 32 do not lie in the same plane but extend at a slight angle to each other.- When the head is iitted on the engine, the spring 30 is stressed so that its oppositely, extending portions 36--40 and 38-42 lie in the same plane. The effect of this is to cause the springto at .all times hold the plungers in engagelinent with the tappet and valve respectlvely.

It will be noted that the fork 26 is not located midway between the plungers. It is,

however, located along the nodal line determined by the relative displacements of the plungers as previously described; thus, since 4the plunger 10 is of greater displacement,

sequently silent in operation. At te same time, the spring serves as a convenient means Afor attaching the plungers tothe head so that the entirehydraulic apparatus may be removed from the engine wlthout any possibility of oil being spilled.

It may be mentioned that for short intervals the spring willbe subjected to eriodic Y flexing; thus should the'chamber 14 e completely or partly empty of oil the motion of the operating plunger will be' transmitted only in part, if at all, to the operated plunger, the result being that the spring 30 will be flexed about 'its axis. However, it will continue tourge the operating plunger outwardly of the chamber causing an effective pumping action which, aftera few strokes, will draw oil into the chamber from the reservoir 16. When thechamber 14 is filled with oil, the spring 30 will again perform a simple. rocking movement.

In Figures 4 and 5 l have illustrated a slightly modied construction. Here the spring 50 is in the form of a flat leaf, normally distorted as shown 'in Figure 4, but

forcedto lie'in. a single plane when the gear 'is mounted on' -the engine. 52 indicates an angle bracket secured to the bottom of the reservoir 16, having its downwardly extending arm 54 perforated as at 56 to receive the v spring and provide a fulcrum therefor. The

ends of the spring are notched as at 58 to ftv pistons. The operation of this construction irre'aaaa of spring is identical with the operation ot the form shown in the preceding figures.

The invention herein disclosed may take various other forms and the claims consequently are not limited to the precise design shown.

I claim:

1. The combination of an operating plunger, an operated plunger, an hydraulic chamber containing a body of fluid interposed between said plungers for transmitting movement from one to the other and a rocker spring engaging said plungers, said spring being normally under stress so as to continuously urge said plungers outwardly of the chamber.

2. In the combination as 'dened in .claim 1, said plungers being of unequal displacement, and the axis of said rocker Vspring lying nearer the piston of greater displace ment so that the normalaction of the spring is purely a rocking action.

3. ln the combination as defined in claim 1, the axis of said rocker spring being located at a nodal point determined by the length of stroke of said plungers so that there is no periodic distortion of the spring in normal operation.

4. Hydraulic. operating mechanism comprising an operating part, an operated part, an hydraulic chamber containing a body of fluid interposed between said parts for transmitting motion from one to the other by displacement of the iiuid in the chamber and..

common means for yieldin ly urging lsaid parts outwardly of the cham er.

5. Valve mechanism comprising a valve, a

tappet, an operating plunger engaged by the tappet, an operated plunger engaged by the valve, an hydraulic `chamber containing a body of fluid interposed between said plunge'rs and a spring engaging said plungers and normally urging them outwardly of the chamber.

6. In the combination as deiined in claim 5, said spring being in the form .of a rocker pivoted at a nodal point determined by the length of stroke of the plungers so that the normal action of the spring is purely a rocking action.

7. ln the combination Tas defined in claim 5, said springhaving its ends connected to said plungers and provided with an intermediate portion forming a fulcrum anda bearing for said intermediate portion. n

8. The combination of a motor comprising a cylinder, a piston in the cylinder, a valve for the cylinder, a push rod for operating the valve, hydraulic devices for transmitting movement from the push rod to the valve `comprising a head adaptedto be removabler attached "to theengine and formed to provide an hydraulic chamber having guides communicating therewith, plungers in said guides, one ot said plungers engaging said tappet and the other said valve, and means secured to said head and engaging said plungers to retain the plungers in the guides upon removal of the head from the engine.

9. In the combination as dened in claim 8, said means comprising a resilient member normally urging the plungers into engagement with said tappet and valve respectively.

10, In the combination as defined in claim 8, said means comprising a rocker spring 'having its ends in engagement with said tappet and valve respectively, said spring being normally stressed to hold said plungers in engagement with the tappet and valve respectively.

11. ln the combination as defined in claim 8, said means comprising a rocker spring having its ends in engagement with said tappet and valve respectively, said spring being normally stressed to hold said plungers in engagement with the tappet and valve respectively, and the rocker axis being located at a nodal point determined by the lengths of the strokes of the plungers.

12. A torsion spring havingaan intermediate transverse portion forming a pivot,re turn bent portions at the ends of the intermediateportion, said portions terminating in longitudinal extensions adapted for connection to suitable parts.

13. ln the combination as defined in claim l2, said spring having a slight camber.

lll. Hydraulic valve operating mechanism comprising a valve, a spring for urging the valve against its seat, a. tappet, a cam, a spring 'or holding the tappet against the cam, an operating plunger engaged by the tappet, an operated plunger engaged by the valve, an hydraulic chamber containing a body of liui'd interposed between said plungers, and a rocker spring having its ends engagin said plungers and being normally assembled in distorted position so that it yieldingly urges at least one ot said plungers against its contacting member.

15. ln the combination as defined in claim ylll, said rocker spring being pivoted at a point intermediate the plungers determined by the relative extent or movement of the operating and operated plungers so that it is sub- `ject to pure rockin action only during the operation of the va ve gear.

16. In valve operating gear the combina` tion ef a plurality of reciprocating parts and .for transmitting motion from one to the other. l.

18. The combination of a pair of reciprocating parts, a torsion spring confined for movement about its torsional axis, said spring being normally stressed so as to exert pres-l sure on said parts and having its ends engaging said parts for transmitting motion from one tothe other.

10' 19. In valve operating mechanism, the

combination of an operating part, an operated part, a spring member including a pivotally monted transversely extending torsional portion and oppositely extending 15 ends in engagement with said parts for transmitting motion from one to the other, saidl transversely extending torsional portion being form'ed of spring material and adaptedl to transmit torsional strain from one end of 20 the member to the other.

In testimony whereof I aiix my signature.

' GEORGE E. A. HALLETT. 

